- AMINE-BORANES AS BIFUNCTIONAL REAGENTS FOR DIRECT AMIDATION OF CARBOXYLIC ACIDS
-
The present invention generally relates to a process for selective and direct activation and subsequent amidation of aliphatic and aromatic carboxylic acids to afford an amide R3CONR1R2. That the process is capable of delivering gaseous or low-boiling point amines provides a major advantage over existing methodologies, which involves an intermediate of triacyloxyborane-amine complex [(R3CO2)3—B—NHR1R2]. This procedure readily produces primary, secondary, and tertiary amides, and is compatible with the chirality of the acid and amine involved. The preparation of known pharmaceutical molecules and intermediates has also been demonstrated.
- -
-
Paragraph 0008-0009; 0063-0064
(2022/03/04)
-
- NaOTs-promoted transition metal-free C-N bond cleavage to form C-X (X = N, O, S) bonds
-
Multifunctional transformation of amide C-N bond cleavage is reported. The protocol applies to benzamide, thioamide, alcohols, and mercaptan under similar reaction conditions catalyzed by NaOTs. It is noteworthy that NaOTs can not only be recycled and reused for up to three cycles without significant loss in catalytic activity, but also catalyze gram-grade reactions. This study provides a novel solution with mild conditions and a simple procedure for transformation of multiple amides.
- Chen, Wei,Liu, Sicheng,Liu, Tingting,Majeed, Irfan,Ye, Xiaojing,Zeng, Zhuo,Zhang, Yuqi,Zhu, Yulin
-
p. 8566 - 8571
(2021/10/20)
-
- Amine-boranes as Dual-Purpose Reagents for Direct Amidation of Carboxylic Acids
-
Amine-boranes serve as dual-purpose reagents for direct amidation, activating aliphatic and aromatic carboxylic acids and, subsequently, delivering amines to provide the corresponding amides in up to 99% yields. Delivery of gaseous or low-boiling amines as their borane complexes provides a major advantage over existing methodologies. Utilizing amine-boranes containing borane incompatible functionalities allows for the preparation of functionalized amides. An intermolecular mechanism proceeding through a triacyloxyborane-amine complex is proposed.
- Choudhary, Shivani,Hamann, Henry J.,Ramachandran, P. Veeraraghavan
-
supporting information
(2020/11/13)
-
- Kinetic study on nucleophilic displacement reactions of 2-chloro-4-nitrophenyl x-substituted-benzoates with primary amines: Reaction mechanism and origin of the a-effect
-
Second-order rate constants for aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (1a-h) have been measured spectrophotometrically in 80 mol % H2O/20 mol % DMSO at 25.0 °C. The Bronsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (1d) with a series of primary amines curves downward, which has been taken as evidence for a stepwise mechanism with a change in rate-determining step (RDS). The Hammett plots for the reactions of 1a-h with hydrazine and glycylglycine are nonlinear while the Yukawa- Tsuno plots exhibit excellent linearity with ρX = 1.22-1.35 and r = 0.57-0.59, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by stabilization of substrates possessing an electron-donating group (EDG) through resonance interactions between the EDG and C=O bond of the substrates. The α-effect exhibited by hydrazine increases as the substituent X changes from a strong EDG to a strong electron-withdrawing group (EWG). It has been concluded that destabilization of hydrazine through the electronic repulsion between the adjacent nonbonding electrons is not solely responsible for the substituent dependent α-effect but stabilization of the transition state is also a plausible origin of the α-effect.
- Um, Tae-Il,Kim, Min-Young,Kim, Tae-Eun,Um, Ik-Hwan
-
p. 436 - 440
(2014/03/21)
-
- pKa-dependent formation of amides in water from an acyl phosphate monoester and amines
-
(Chemical Equation Presented) Acyl phosphate monoesters are readily prepared biomimetically activated anionic derivatives of carboxylic acids that react rapidly with amines in water to form amides. A plot of the logarithms of the rate constants for the reactions of a series of primary amines with benzoyl methyl phosphate depends on the pKa of the conjugate acids of the amines (βnuc ≈ 0.9). This provides a simple and quantitative basis for regioselective acylation with these reagents.
- Wodzinska, Jolanta,Kluger, Ronald
-
p. 4753 - 4754
(2008/09/21)
-
- N-(Benzoyloxy)amines: An investigation of their thermal stability, synthesis, and incorporation into novel peptide constructs
-
A series of N-benzoyloxyamines were pyrolyzed and their decomposition temperatures correlated well with the amine architecture's ability to stabilize a N-centered radical. A variety of amine substrates were treated with a biphasic mixture of benzoyl peroxide (BPO), CH2Cl2 and an aqueous carbonate buffer (at pH 10.5). Primary and secondary amines were successfully N-benzoyloxylated in good yield. Tertiary amines and BPO gave low yields of the corresponding N-oxide and complex product mixtures, presumably via radical decomposition. Electron deficient amines (such as fluorinated aliphatic amines, α-aminoacids, α-aminoesters, and α-aminoamides) were not N-benzoyloxylated under these conditions. Instead, N-benzoylation was observed with the fluorinated amines and the reaction was sensitive to temperature and the pH of the aqueous medium. A one-pot-two-step synthesis of Nα-FMOC-L-Leu-Nβ-(benzoyloxy)-β-alanine ethyl ester, a peptide containing both an α- and a novel β-amino acid framework, was also developed.
- Nemchik, Anne,Badescu, Valentina,Phanstiel IV, Otto
-
p. 4315 - 4325
(2007/10/03)
-
- Biomimetic reductive amination of perfluoroalkylcarboxylic acids to α,α-dihydroperfluoroalkylamines
-
The first general method for the reducing reagent-free, biomimetic transformation of perfluorocarboxylic acids to the α,α-dihydroperfluoroalkyl amines is reported. High chemical yields and simplicity of the experimental procedure render this method immediately useful and synthetically superior to the conventional approaches relying on application of reducing reagents.
- Soloshonok, Vadim A,Ohkura, Hironari,Uneyama, Kenji
-
p. 5449 - 5452
(2007/10/03)
-
- Kinetics of Aminolysis of some Benzoyl Fluorides and Benzoic Anhydrides in Non-hydroxylic Solvents
-
The kinetic form of the spontaneous aminolysis of benzoyl fluorides in non-hydroxylic solvents is unlike that reported for the other benzoyl halides, but is similar to that found for the aminolysis of esters.Variations on the mechanisms currently advocated for ester aminolysis are suggested for the benzoyl fluoride reactions.Tetrahedral intermediates are likely, but their rate-determining breakdown to products may involve a simultaneous proton transfer to the leaving fluoride ion.The kinetic behaviour differs from that found for aqueous solutions.The kinetics of the spontaneous aminolysis of benzoic anhydrides by primary amines, and by morpholine, in dioxane solution are first-order in each reagent over a wide amine concentration range, but the aminolysis by imidazoles involves also an important kinetic term second-order in amine.The mechanistic implications are discussed.Again the observations differ from some of those reported for aqueous solutions.For aminolyses of a variety of acylating agents, kinetic observations using non-hydroxylic solvents show that the easier it is for the leaving group to depart, owing to the structure of the acylating agent and/or that of the attacking amine, the less important become paths involving two or more amine molecules, but that such paths are generally more important than they are in hydroxylic solvents.
- Jedrzejczak, Maria,Motie, Richard E.,Satchell, Derek P. N.,Satchell, Rosemary S.,Wassef, Wasfy N.
-
p. 1471 - 1480
(2007/10/02)
-